[Isolation and sequencing of glucoamylase gene from a glucoamylase over producing strain]

Chromosomal DNA was isolated from the mycelia of Aspergillus niger T21, a strain producing glucoamylase at a high level. Southern blot analysis indicated that the glucoamylase gene is situated on a 2.5kb EcoR I -EcoR V fragment. Chromosomal DNA was digested completely with EcoR I, EcoR V. The fragments in the range of 2.0-3.0kb were isolated through electrophoresis in agarose gel. The pooled fragments were ligated onto pBR322 vector prior to transformation into E. coli DH5. Four glucoamylase-specific recombinants were screened by in situ hybridization from the transformants. Restriction mapping and sequencing for one of the four were performed. Data show that the glucoamylase gene from A. niger T21 is a 2.3kb fragment containing four intervening sequences in the coding region.